PREPARATION AND CHARACTERIZATION OF ACTIVATED CARBONS FROM ANTHRACITE

A single-step pyrolysis/activation was used to produce activated carbons from a Pennsylvania anthracite. Steam was employed as the principal activation agent, although some experiments were carried out using air activation prior to the reaction with steam. Activated carbons produced from two different particle size ranges of the starting anthracite (1-3 mm and <1 mm) showed relatively high N2 BET surface areas depending on the pyrolysis/activation conditions. The highest BET surface area carbon (720 m2/g) was obtained from the anthracite with particle size <1 mm. The particle size of the starting anthracite was found to be the most important variable which affects the adsorption properties of the resulting carbons. The initial reaction of the anthracite with air leads to an increase in the solid yields with comparable adsorption parameters for the steam activated anthracite with highest N2 surface area produced at treatment temperature of 850-degrees-C for 6 h from fine particles. Microscopic examination of activated carbons showed a highly anisotropic attack of steam on the active edges of anthracite particles. This preferential attack produced highly asymmetrical needlelike particles. Air activation results in more isotropic activation of the anthracite surfaces.